Sunday, March 1, 2020

Unsurprisingly, gravity still works at 52 micrometers

While it is important to experimentally determine at what scales we can confirm that gravity behaves as expected in Newtonian gravity and general relativity, nobody had any good reason to think that it would break down at short distances on the order of  roughly a 200th of a millimeter or longer. 

Any short distance, weak field quantum gravity effects wouldn't be expected at any scale significantly above the femtometer scale and possibly only at a scale comparable to the Planck length, which are many, many orders of magnitude smaller.

New Test of the Gravitational 1/r2 Law at Separations down to 52 μm

We tested the gravitational 1/r2 law using a stationary torsion-balance detector and a rotating attractor containing test bodies with both 18-fold and 120-fold azimuthal symmetries that simultaneously tests the 1/r2 law at two different length scales. We took data at detector-attractor separations between 52 μm and 3.0 mm. Newtonian gravity gave an excellent fit to our data, limiting with 95\% confidence any gravitational-strength Yukawa interactions to ranges <38.6 μm.
Comments:5 pages, 5 figures
Subjects:High Energy Physics - Experiment (hep-ex); Instrumentation and Detectors (physics.ins-det)
Cite as:arXiv:2002.11761 [hep-ex]
 (or arXiv:2002.11761v1 [hep-ex] for this version)


neo said...

what would a hypothetical experiment results would be if somehow this experiment could be done in the MOND acceleration regime, i.e how would newton prediction differ from MOND in the putative MOND regime?

andrew said...

In very weak fields, MOND would predict a pull of gravity that was stronger than Newtonian gravity. But, almost by definition, extremely short distances are not in the MOND regime because gravitational fields are stronger at short distances.

More generally, quantum gravity should have features at long distances that QCD displays at short distances.

neo said...

how could an experiment be done to test this, such as flying a satellite out of the solar system? and could any stronger pull be explained in terms of dark matter?